Optaplanner - Real-time planning doesn't find good solution

Question

I am trying to use real time planning using a custom SolverThread implementing SolverEventListener and the daemon mode.

I am not interested in inserting or deleting entities. I am just interested in "updating" them, for example, changing the "priority" for a particular entity in my PlanningEntityCollectionProperty collection.

At the moment, I am using:

scoreDirector.beforeProblemPropertyChanged(entity);
entity.setPriority(newPriority);
scoreDirector.afterProblemPropertyChanged(entity);

It seems that the solver is executed and it manages to improve the actual solution, but it only spends a few ms on it:

org.optaplanner.core.impl.solver.DefaultSolver: Real-time problem fact changes done: step total (1), new best score (0hard/-100medium/-15soft).
org.optaplanner.core.impl.solver.DefaultSolver: Solving restarted: time spent (152), best score (0hard/-100medium/-15soft), environment mode (REPRODUCIBLE),

Therefore, the solver stops really soon, considering that my solver has a 10 seconds UnimprovedSecondsSpentLimit. So, the first time the solver is executed, it stops after 10 seconds, but the following times, it stops after a few ms and doesn't manage to get a good solution.

I am not sure I need to use "beforeProblemPropertyChanged" when the planning entity changes, but I can't find any alternative because "beforeVariableChanged" is used when the planning variable changes, right? Maybe optaplanner just doesn't support updates in the entities and I need to delete the old one using beforeEntityRemoved and inserted it again using beforeEntityAdded?

I was using BRANCH_AND_BOUND, however, I have changed to local search TABU_SEARCH and it seems that the scheduler uses 10 seconds now. However, it seems stuck in a local optima because it doesn't manage to improve the solution, even with a really small collection (10 entities).

Anyone with experience with real time planning? Thanks

What do you see when you turn on DEBUG logging and remove the classname output from the log pattern? — Geoffrey De Smet

Geoffrey De Smet Geoffrey De Smet · Accepted Answer · 2018-01-29T10:47:01

The "Solving restarted" always follows very shortly after "Real-time problem fact changes done", because real-time problem facts effectively "stop & restart" the solver. The 10 sec unimproved termination only starts counting again after the restart.

DEBUG logging (or even TRACE) will show you what's really going on.

Optaplanner - Real-time planning doesn't find good solution

1 Answers